Return-path: Received: from mail-qw0-f46.google.com ([209.85.216.46]:36544 "EHLO mail-qw0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758613Ab1DMXHS convert rfc822-to-8bit (ORCPT ); Wed, 13 Apr 2011 19:07:18 -0400 MIME-Version: 1.0 In-Reply-To: References: <1302566227-23788-1-git-send-email-zajec5@gmail.com> <20110412133633.GR15130@legolas.emea.dhcp.ti.com> <1302634039.14216.10.camel@dev.znau.edu.ua> <1302635550.14216.21.camel@dev.znau.edu.ua> <4DA4AC4B.90409@hauke-m.de> <1302640546.14216.65.camel@dev.znau.edu.ua> <1302726187.7911.11.camel@dev.znau.edu.ua> Date: Thu, 14 Apr 2011 01:07:17 +0200 Message-ID: Subject: Re: [RFC][PATCH] axi: add AXI bus driver From: =?UTF-8?B?UmFmYcWCIE1pxYJlY2tp?= To: George Kashperko Cc: Arend van Spriel , "balbi@ti.com" , "linux-wireless@vger.kernel.org" , "John W. Linville" , "b43-dev@lists.infradead.org" , =?UTF-8?Q?Michael_B=C3=BCsch?= , Larry Finger , "linux-arm-kernel@lists.infradead.org" , Russell King , Arnd Bergmann , Andy Botting , linuxdriverproject , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-wireless-owner@vger.kernel.org List-ID: 2011/4/13 Rafał Miłecki : > 2011/4/13 Rafał Miłecki : >> Will comment on that later. > > Can we try to decide, how to implement our driver correctly? This > should be main focus for now. I tried to analyze drivers/amba/, how it > works, how it relates to our code, Broadcom. > > AFAICS AMBA so far is mostly (always?) used for embedded devices with > pre-defined hardware layout. Let's take as example mach-u300 (just > some random one). One of the amba_devices it registers is uart0_device > which has two interesting fields: > .start = U300_UART0_BASE, > .end   = U300_UART0_BASE + SZ_4K - 1, > U300_UART0_BASE == (U300_SLOW_PER_PHYS_BASE+0x3000) == 0xc0013000 > So this mach-u300 is well-specified device, every mach-u300 has uart0 > at 0xc0013000. > > It looks every AMBA device (like uart0) has some common fields, like: > u32 peripherialid0, peripherialid1, peripherialid2, peripherialid3; > u32 componentid0, componentid1, componentid2, componentid3; > > I believe Broadcom's *agent* AKA *wrapper* is comparable to standard > amba device. > > Of course agents/wrappers are not the same for every Broadcom AMBA AXI > card, so we can not use strict .start and .end declarations and the > same agents/wrappers for every card. Instead, we have to do scanning > of EPROM to read info about agents/wrappers. > > If someone does not know: every core on Broadcom AMBA AXI card has > it's agent/wrapper. We access agent/wrapper registers to > enable/disable/reset core. > > So we could scan EPROM for agents/wrappers, register them in AMBA > driver using our *_core_enable as AMBA's clock management. > > > Please verify if my understanding is correct. I tried to explain > easily whole situation I just analyzed. > > If I'm right: is this really the right path to follow? What about real > core, like PCIe core, or IEEE core? I guess they are not standard AMBA > cores, so we can not simply register them. Should we look for clever > way to connect everything we have with drivers/amba? How to connect > "real" cores (PCIe, IEEE) with agents? > > Please, share how do you see this situation now. I've done a little more thinking & investigation on this. First of all, our agent/wrapper cores are real AMBA components. I've done such a reading: pr_info("XXX wrapper AXI_PERIPHERIALID0 0x%08X\n", axi_aread32(core, AXI_PERIPHERIALID0)); pr_info("XXX wrapper AXI_COMPONENTID0 0x%08X\n", axi_aread32(core, AXI_COMPONENTID0)); for every agent/wrapper. The result was: [ 362.720551] axi: Switched to core: 0x800 [ 362.720519] axi: CC wrapper AXI_PERIPHERIALID0 0x00000069 [ 362.720523] axi: CC wrapper AXI_PERIPHERIALID1 0x000000B3 [ 362.720527] axi: CC wrapper AXI_PERIPHERIALID2 0x0000003B [ 362.720531] axi: CC wrapper AXI_PERIPHERIALID3 0x00000010 [ 362.720535] axi: CC wrapper AXI_COMPONENTID0 0x0000000D [ 362.720539] axi: CC wrapper AXI_COMPONENTID1 0x000000F0 [ 362.720542] axi: CC wrapper AXI_COMPONENTID2 0x00000005 [ 362.720546] axi: CC wrapper AXI_COMPONENTID3 0x000000B1 [ 362.720551] axi: Switched to core: 0x820 [ 362.728037] axi: PCIE wrapper AXI_PERIPHERIALID0 0x00000069 [ 362.728041] axi: PCIE wrapper AXI_PERIPHERIALID1 0x000000B3 [ 362.728045] axi: PCIE wrapper AXI_PERIPHERIALID2 0x0000003B [ 362.728049] axi: PCIE wrapper AXI_PERIPHERIALID3 0x00000010 [ 362.728053] axi: PCIE wrapper AXI_COMPONENTID0 0x0000000D [ 362.728056] axi: PCIE wrapper AXI_COMPONENTID1 0x000000F0 [ 362.728060] axi: PCIE wrapper AXI_COMPONENTID2 0x00000005 [ 362.728064] axi: PCIE wrapper AXI_COMPONENTID3 0x000000B1 [ 362.728068] axi: Switched to core: 0x812 [ 362.728076] axi: 80211 wrapper AXI_PERIPHERIALID0 0x00000069 [ 362.728079] axi: 80211 wrapper AXI_PERIPHERIALID1 0x000000B3 [ 362.728083] axi: 80211 wrapper AXI_PERIPHERIALID2 0x0000003B [ 362.728087] axi: 80211 wrapper AXI_PERIPHERIALID3 0x00000010 [ 362.728091] axi: 80211 wrapper AXI_COMPONENTID0 0x0000000D [ 362.728095] axi: 80211 wrapper AXI_COMPONENTID1 0x000000F0 [ 362.728098] axi: 80211 wrapper AXI_COMPONENTID2 0x00000005 [ 362.728102] axi: 80211 wrapper AXI_COMPONENTID3 0x000000B1 Tip: #define AMBA_CID 0xb105f00d *So*: 1) We could read info about existing agents/wrappers from EPROM and register them as amba_devices 2) We could register amba_driver for id 0x103BB369 3) We could register our core-managing functions as clock operators Problem: b43 can not be our amba_driver, because this is not the correct layer. We would need to create separated amba_driver driver for 0x103BB369, initializing whole stuff (PCIe core, ChipCommon, ChipCommon PMU) *and* registering new kind of device in the system, identified by manuf, id, rev and class. That devices would be of course Broadcom cores present on AMBA, but not AMBA-compatible (not wrappers, they are real AMBA devices!). I've also try treating Broadcom cores (not wrappers, which are real AMBA devices!) as AMBA devices. For that I've tried: pr_info("80211 AXI_PERIPHERIALID0 0x%08X\n", axi_read32(core, AXI_PERIPHERIALID0)); Please, note, that this time I used "read32", not "aread32". It means I was accessing Broadcom core, not AMBA agent/wrapper core. This operation hanger my machine right away. -- Rafał